Of nine ependymoma molecular groups detected by DNA methylation profiling, the posterior fossa type A (PFA) is most prevalent.
Ependymomas occur in both the brain and spine. The prognosis of these tumors sometimes differs for different locations. The genetic landscape of ependymoma is very heterogeneous despite the similarity of histopathologic findings.
In a review, Lee et al. describe the genetic differences between spinal ependymomas and their intracranial counterparts to better understand their prognosis. From the literature review, many studies have reported that spinal cord ependymoma might be associated with NF2 mutation, NEFL overexpression, Merlin loss, and 9q gain. In myxopapillary ependymoma, NEFL and HOXB13 overexpression were reported to be associated. Prior studies have identified HIC-1 methylation, 4.1B deletion, and 4.1R loss as common features in intracranial ependymoma. Supratentorial ependymoma is usually characterized by NOTCH-1 mutation and p75 expression. TNC mutation, no hypermethylation of RASSF1A, and GFAP/NeuN expression may be diagnostic clues of posterior fossa ependymoma. Although MEN1, TP53, and PTEN mutations are rarely reported in ependymoma, they may be related to a poor prognosis, such as recurrence or metastasis. Spinal ependymoma has been found to be quite different from intracranial ependymoma in genetic studies, and the favorable prognosis in spinal ependymoma may be the result of the genetic differences. A more detailed understanding of these various genetic aberrations may enable the identification of more specific prognostic markers as well as the development of customized targeted therapies 1).
Ependymoblastoma, an aggressive embryonal tumor containing multilayered (ependymoblastic) rosettes in addition to primitive small round blue cells, is now considered a form of primitive neuroectodermal tumor.
Histopathological classification is not sufficient to show variable outcomes, and fails to show prognostic markers of the diverse outcomes; hence, it is essential to understand biological mechanisms.